Hi Sven, On Sun, Feb 12, 2017 at 12:16:17PM +0100, Sven Schmidt wrote: > > > > On 02/10/2017 01:13 AM, Minchan Kim wrote: > > Hello Sven, > > > > On Thu, Feb 09, 2017 at 11:56:17AM +0100, Sven Schmidt wrote: > >> Hey Minchan, > >> > >> On Thu, Feb 09, 2017 at 08:31:21AM +0900, Minchan Kim wrote: > >>> Hello Sven, > >>> > >>> On Sun, Feb 05, 2017 at 08:09:03PM +0100, Sven Schmidt wrote: > >>>> > >>>> This patchset is for updating the LZ4 compression module to a version based > >>>> on LZ4 v1.7.3 allowing to use the fast compression algorithm aka LZ4 fast > >>>> which provides an "acceleration" parameter as a tradeoff between > >>>> high compression ratio and high compression speed. > >>>> > >>>> We want to use LZ4 fast in order to support compression in lustre > >>>> and (mostly, based on that) investigate data reduction techniques in behalf of > >>>> storage systems. > >>>> > >>>> Also, it will be useful for other users of LZ4 compression, as with LZ4 fast > >>>> it is possible to enable applications to use fast and/or high compression > >>>> depending on the usecase. > >>>> For instance, ZRAM is offering a LZ4 backend and could benefit from an updated > >>>> LZ4 in the kernel. > >>>> > >>>> LZ4 homepage: http://www.lz4.org/ > >>>> LZ4 source repository: https://github.com/lz4/lz4 > >>>> Source version: 1.7.3 > >>>> > >>>> Benchmark (taken from [1], Core i5-4300U @1.9GHz): > >>>> ----------------|--------------|----------------|---------- > >>>> Compressor | Compression | Decompression | Ratio > >>>> ----------------|--------------|----------------|---------- > >>>> memcpy | 4200 MB/s | 4200 MB/s | 1.000 > >>>> LZ4 fast 50 | 1080 MB/s | 2650 MB/s | 1.375 > >>>> LZ4 fast 17 | 680 MB/s | 2220 MB/s | 1.607 > >>>> LZ4 fast 5 | 475 MB/s | 1920 MB/s | 1.886 > >>>> LZ4 default | 385 MB/s | 1850 MB/s | 2.101 > >>>> > >>>> [1] http://fastcompression.blogspot.de/2015/04/sampling-or-faster-lz4.html > >>>> > >>>> [PATCH 1/5] lib: Update LZ4 compressor module > >>>> [PATCH 2/5] lib/decompress_unlz4: Change module to work with new LZ4 module version > >>>> [PATCH 3/5] crypto: Change LZ4 modules to work with new LZ4 module version > >>>> [PATCH 4/5] fs/pstore: fs/squashfs: Change usage of LZ4 to work with new LZ4 version > >>>> [PATCH 5/5] lib/lz4: Remove back-compat wrappers > >>> > >>> Today, I did zram-lz4 performance test with fio in current mmotm and > >>> found it makes regression about 20%. > >>> > >>> "lz4-update" means current mmots(git://git.cmpxchg.org/linux-mmots.git) so > >>> applied your 5 patches. (But now sure current mmots has recent uptodate > >>> patches) > >>> "revert" means I reverted your 5 patches in current mmots. > >>> > >>> revert lz4-update > >>> > >>> seq-write 1547 1339 86.55% > >>> rand-write 22775 19381 85.10% > >>> seq-read 7035 5589 79.45% > >>> rand-read 78556 68479 87.17% > >>> mixed-seq(R) 1305 1066 81.69% > >>> mixed-seq(W) 1205 984 81.66% > >>> mixed-rand(R) 17421 14993 86.06% > >>> mixed-rand(W) 17391 14968 86.07% > >> > >> which parts of the output (as well as units) are these values exactly? > >> I did not work with fio until now, so I think I might ask before misinterpreting my results. > > > > It is IOPS. > > > >> > >>> My fio description file > >>> > >>> [global] > >>> bs=4k > >>> ioengine=sync > >>> size=100m > >>> numjobs=1 > >>> group_reporting > >>> buffer_compress_percentage=30 > >>> scramble_buffers=0 > >>> filename=/dev/zram0 > >>> loops=10 > >>> fsync_on_close=1 > >>> > >>> [seq-write] > >>> bs=64k > >>> rw=write > >>> stonewall > >>> > >>> [rand-write] > >>> rw=randwrite > >>> stonewall > >>> > >>> [seq-read] > >>> bs=64k > >>> rw=read > >>> stonewall > >>> > >>> [rand-read] > >>> rw=randread > >>> stonewall > >>> > >>> [mixed-seq] > >>> bs=64k > >>> rw=rw > >>> stonewall > >>> > >>> [mixed-rand] > >>> rw=randrw > >>> stonewall > >>> > >> > >> Great, this makes it easy for me to reproduce your test. > > > > If you have trouble to reproduce, feel free to ask me. I'm happy to test it. :) > > > > Thanks! > > > > Hi Minchan, > > I will send an updated patch as a reply to this E-Mail. Would be really grateful If you'd test it and provide feedback! > The patch should be applied to the current mmots tree. > > In fact, the updated LZ4 _is_ slower than the current one in kernel. But I was not able to reproduce such large regressions > as you did. I now tried to define FORCE_INLINE as Eric suggested. I also inlined some functions which weren't in upstream LZ4, > but are defined as macros in the current kernel LZ4. The approach to replace LZ4_ARCH64 with the function call _seemed_ to behave > worse than the macro, so I withdrew the change. > > The main difference is, that I replaced the read32/read16/write... etc. functions using memcpy with the other ones defined > in upstream LZ4 (which can be switched using a macro). > The comment of the author stated, that they're as fast as the memcpy variants (or faster), but not as portable > (which does not matter since we're not dependent for multiple compilers). > > In my tests, this version is mostly as fast as the current kernel LZ4. With a patch you sent, I cannot see enhancement so I wanted to dig in and found how I was really careless. I have tested both test with CONFIG_KASAN. OMG. With disabling it, I don't see any regression any more. So, I'm really really *sorry* about noise and wasting your time. However, I am curious why KASAN makes such difference. The reason I tested new updated lz4 is description says lz4 fast and want to use it in zram. How can I do that? and How faster it is compared to old? Thanks for you work!
